Conveyor systems which utilize endless belts for the transport or movement of materials from one location to another are used widely in industry. The belts may either be flat, in cross section, or may be concave or dish-shaped in section to more effectively transport particulate, that is, loose, bulk material. Flexible, endless belts are normally supported and directed by idler rollers, both in the delivery and return runs. And, of course, the belt and rollers are carried on suitable base support structure.
Since belt conveyor systems are frequently of great length, it occurs that changes in direction must be provided for. Thus, the situation arises where the belt is required to travel in other than a linear path while moving material in a horizontal plane. In conveyor systems for transporting bulk materials, the carrying structure is normally provided with idler rollers that form a trough-like area or concavity which receives an endless belt which is upwardly concave in cross section. In those situations where the conveyor belt must traverse curves in the horizontal plane, the tension in the longitudinal direction of the conveyor belt is uneven across the width of the belt. In order to cause the belt to follow a curved path, the rollers that support the weight of the belt and the material on the belt must also exert a lateral thrust against the belt in a direction away from the center of the curve of the belt path. The amount of this lateral thrust changes as the belt tension changes and as the weight of the material on the belt changes.
In the past, it has been proposed to compensate for the changes in lateral thrust by suspending the endless belt from a hanger arrangement so that the belt is in effect acting as a pendulum and is free to swing to and fro depending upon the lateral forces generated by the belt and the load carried on the belt. An arrangement such as this may be acceptable where space is available to permit free lateral movement of the belt about a fixed pivot or fulcrum point.
In contradistinction to those situations where space is not at a premium, there are many uses where endless conveyors are involved where space is quite limited. For example, in mining operations and in the removal of rock and other byproducts resulting from underground excavation such as in the digging of tunnels or other subterranean passageways, space is usually critical. In the case of tunnel excavation, for example, space is indeed at a premium because the hole being excavated is of limited size and not only must the excavated material be removed but other equipment such as drill heads, rail cars, etc. must also be accommodated within the same limited space. Problems are therefore encountered with regard to the space available for the installation of a conveyor system by means of which removal of bulk material can be accomplished.
It is a principal object of this invention to provide an improved belt supporting a guiding apparatus for use in utilizing an endless belt which travels in other than a straight line in the horizontal plane.
Another object of this invention is to provide a belt supporting apparatus in which an endless belt can convey material along a curved path.
An additional object of this invention is to provide a belt supporting apparatus in which an endless belt is supported by structure that enables the belt to self-adjust its spatial orientation when travelling in other than a straight line in the horizontal plane.
A further object of this invention is to provide a belt supporting apparatus in which support means are provided which enables an endless, load carrying belt to tilt from the horizontal plane when travelling in other than a straight line.
Yet another object of this invention is to provide support structure for an endless conveyor belt in which the belt is cradled in a concavity defined by a rotatably mounted frame.
Another important object of this invention is to provide rotatable support structure for an endless belt in a conveyor system in which the belt support structure requires minimal space for rotation.
A still further object of this invention is to provide a conveyor system having an endless belt support structure that rotates about an axis defining an instant center, the location of which center changes in space with each increment of rotation of the support structure.